How Does Agnps Enhance Luminol Fluorescence

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Recent research shows that AgNPs enhance luminol fluorescence and chemiluminescence by acting as a catalyst with hydrogen peroxide. When AgNPs interact with hydrogen peroxide they cause the peroxide to degrade into superoxide and hydroxyl radical, which also react with luminol to form 3-aminophthalate (Equations 2-5) [13]. The further degradation of hydrogen peroxide into other reactive oxygen species promotes higher fluorescence intensity. Figure 5 shows the increased fluorescence intensity of luminol, AgNPs and hydrogen peroxide in solution. However, when strontium is present in solution, the fluorescence intensity decreased to the same intensity promoted by hydrogen peroxide when AgNPs are not present. The strontium not only causes …show more content…
Both divalent cations enter the plant’s roots via macro-sized nutrient pores and continue through the plant by two modes of transportation: apoplastic and symplastic pathways. The apoplastic pathway is the non-selective pathway that silver also uses to move between the cells. This is only restricted by any interactions with the cell membranes lining this pathway. The symplastic pathway utilizes ionic channels and protein pumps [15]. For cellular uptake of strontium and calcium, cells may use non-specific ion pumps or element specific channels that only remove strontium and calcium from the nutrient …show more content…
The varying concentration of Sr and Ca do not cause change in the production of ROS. In this instance the ROS production fluorescence is not dependent on the dication concentration. When the AgNPs are in solution with calcium (Ecell=-1.27, ΔG=2.45E5J), they undergo the same agglomeration process as promoted by strontium (Ecell= -1.3v, ΔG=2.5E5J). These dications both cause a reduction in the fluorescence produced by the agglomerated nanopaticles as their concentration increases. When these solutions interact with the plant leaf disks, the production of ROS decreases with increased divalent cation solutions. The AgNPs are not only increased in size with the addition of these dications that prevent further penetration into the plant cells but also there is less surface area for the AgNPs to apply its antimicrobial abilities to the interior of the plant. This reduction of surface area also restricts the catalytic activity of AgNPs with the degredation of hydrogen peroxide. This decreases the production of other ROS within the plant and inhibits the AgNPs oxidation into its ion counter parts. The decreased prevelance of a variety of ROS and both silver forms within the leaves helps to explain that the existance of dications are useful in reducing toxicity of AgNPs in a phytoremediation

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